Quickest way to identify yourself as a theater tech is to wear black clothing and use duct tape (aka gaffers tape) for bandages.
Over the years I’ve discovered that WD40 can work wonders on scratched transparent plastic. Spray some on. Use your fingers to rub it in, and then wipe most of it off with a rag. Scratches are much less noticable. Works great on scratched turntable plastic covers. Removes stickers pretty good too.
Spoons serve all sorts of uses in jail – not all of them involving bloodshed.
Bent spoon + cut extension cord + coffee cup = electric kettle.
May I ask how?
With the caveat that it’s unreasonably dangerous and should therefore not actually be done by anyone:
The spoon is bent in such a way that the handle hooks over the edge of a cup filled with water, while the business end depends into the inside. The cord is fixed to the handle at the top and bottom, and then plugged in. The spoon heats up, and when the water boils, the cord is unplugged and the works are removed from the cup and left to cool on concrete or porcelain. Hot bevvies can now be enjoyed.
Thank you Thank you Thank you Thank you I’ll be using that real soon.
Oh, and I use a pizza cutter to cut my brownies, cause I like them kinda gooey and other cutters just drag them to pieces. You have to use a knife at the edges of the pan, but that part’s cooked solid, so it’s ok.
I use WD-40 as starting fluid for diesel engines. It won’t vapor lock the engine lick real starting fluid does.
Speaking of starting fluid, don’t get me started on off-label uses for ether. 
You can make some hellaciously good jack-o-lanterns with a Roto-zip.
It also works extremely well in starting your lawnmower, weed whacker, etc. for the first time in the Spring. spray a little in the cylinder, replace the spark pluge and giver her a pull.
The lubricant helps create a good seal around the piston rings, WD–40 is flammable to it ignites almost immediately, and by doing so creates a vacuum in the system, pulling fuel in from the carburetor.
I’ve never had to do the excercise (remove plug, spurt in cylinder, replace plug, pull cord) more than twice to get the motor going.
plastic clothes pins and bungee cords to hold baby bottles and plastic tupperware in place in the dishwasher
bra bags for kid spoons and other kid stuff in the dishwasher
ice cube trays for freezing small food “pops” or sauce “pops” (I make coffee “pops” that I pop into roasts)
plastic easter eggs for kid maracas (fill with rice)
tube socks and rice for microwavable heat pads
zip ties for everything (I had a wire shelf over my laundry center and I zip tied baskets to the underside to hold more laundry gear, I zip tie plants to stakes, etc)
If you have a slow moving drain and can leave it alone for a few hours, a gallon of cheap bleach works just as well as a drain cleaner.
Works great when you’re babysitting small children as well. Throw in some Velcro and you can tape them and hang them on the wall where they are easy to find later on.
Ah, I have a new one, forged from desperation:
Paper ‘yard waste’ bags for excess (ie, holiday) cardboard and paper recyclables. The recycle folks can grab the whole bag and go, and those bags are HUGE.
You can buy these yard waste bags in 8-packs locally, since we have curbside yard waste recycling. I bought a pack when I was doing a bunch of yardwork, but I haven’t had to use them! But man, my recycle bins in the house were full to the point we couldn’t get past them (1 upstairs, 1 downstairs) and the big wheeled bin outside was full too. Et voila, a fix.
Hey, for some of us, that stuff is a CAREER. Just for the record, Sculpey III (the stuff that comes in loads of colors) is a lot stronger when baked than the original white-or-terracotta Sculpey. And one caveat - don’t play with this stuff on a finished wood surface, it’ll eat the varnish right off.